I do indeed think you are being judgmental about the friendship part. It sounds like their friendship was strong enough to withstand this difficult event. The therapist made a mistake, an important one. It is not being ignored by the licensing board and presumably he is being disciplined. It sounds like your T has maintained his friendship. That could potentially speak well of him, not ill. It's hard to say for sure with the limited information available.

I think the topic of your T's colleague is an important one to you and could potentially be therapy-interfering unless you bring it up. However, I would suggest a face to face conversation instead of the letter. Also, your T may not have the kind of authority to ask this therapist to leave the practice, even if he wanted to. Many Ts share office space, waiting room, and some costs (like photocopier), but they are essentially all independent practitioners. It is not up to your T to discipline his colleague; the licensing board will take care of that. If your T doesn't want to share space with him, your T could move. This does not sound like it is the case.

The part about your feeling that your T does not want to discuss your sexuality is very important and should be addressed. I don't think that is related necessarily to your T being male. Many male therapists are capable of speaking directly about sexual topics with their clients.